In the fabrication of a metal sheath for a cable, a flat aluminum or steel tape is advanced between a pair of opposed forming rollers having corrugating ribs which mutually cooperate to produce lateral corrugations in the tape prior to the tape being formed about the cable. It is important during the corrugation process to maintain a uniform depth of corrugation across the width of the tape to enhance flexibility of the sheathed cable in the ultimate handling thereof. However, uniform depth of corrugations has been difficult to achieve in the past wherein tapes of different widths must be processed in the same prior art apparatus. After a certain amount of tape has been passed between the rollers of the apparatus, the corrugating ribs of the rollers begin to exhibit wear, particularly in the areas where the tape is normally passed. For instance, if a narrow strip of tape is passed between the rollers, the wear on the corrugating ribs is localized in a correspondingly narrow section of the rollers. Thus, when a tape of a greater width is subsequently passed between the rollers of the apparatus, the depth of corrugation across the width of the wider tape will be non-uniform because of the localized wear of the corrugating ribs produced by the narrower tape. The resultant non-uniformity of the depth of corrugation then necessitates the replacement of the locally-worn corrugating rollers with a new set of rollers for processing the wider tape, resulting in the constant changing of rollers to accommodate tapes of different widths.
In a prior art apparatus of this type, a guide assembly having spaced guide walls is used to guide the tape into position for passage between the forming rollers. To accommodate tapes of different widths within the same apparatus, the guide mechanism is adjustable to permit variation in the space between the guide walls.
In the prior art apparatus, the corrugating rollers of relatively small diameters tended to deflect laterally of the axis thereof which could also result in uneven or non-uniform depth of the corrugations formed across the width of the tape. To eliminate this problem, the corrugating apparatus also typically required at least one set of back-up rollers in face-to-face engagement with the corrugating rollers which supplied sufficient pressure to prevent deflection of the corrugating rollers during the corrugation process. The back-up rollers were positioned parallel to and in pressure-engagement with the corrugating rollers. This arrangement of the back-up rollers caused a considerable amount of noise to be developed during the corrugating operation due to the constant pressure-engagement of the corrugating rollers with the back-up rollers. The back-up rollers also hampered and lengthened the time required for set-up efforts when the corrugating rollers had to be replaced or adjusted.
U.S. Pat. No. 2,047,883 which issued on July 14, 1936, to C. W. Phillips, discloses a rolling mill for reducing the thickness of metal strips. The apparatus includes a pair of back-up rollers mounted in parallel relationship to a pair of working or compression rollers. The back-up rollers preferably are of an intermediate diameter such that they neither readily deflect during a corrugating operation, nor cause stretching and thinning of the tape 20 during the corrugating operation which are fixedly mounted for rotation only, cooperated with the compression rollers to facilitate the rolling operation. The compression rollers are mounted on a conveyor which is shiftable laterally relative to the metal strip and axially with respect to the back-up rollers, to insure uniformity of wear on the working surface of the compression rollers. Since the back-up rollers, which are fixedly mounted, are in constant pressure-engagement with the compression rollers during the rolling operation, it would appear that the rolling operation would have to be interrupted to facilitate lateral movement of the compression rollers.